Horizontal break disconnecting switch



March 14, 1933. A. ALsAKE-R Er A1. 1,901,688

HORIZONTAL BREAK DISCONNECTING SWITCH Filed April 30, 1930 n 3 Sheets-Sheet l 40' 6g yg Z @f 35.

March 14, 1933- A. ALsAKER ET AL HORIZONTAL BREAK DISCONNECTING SWITCH Filed April' 30, 1930 5 SheeS-Sheet- 2 March l 14, 1933. A. ALsAKER Er AL n HORIZONTAL BREAK DISCONNECTING SWITCH Filed April 30, 1930 3 Sheets-Sheet 3 lPatented Mar. 14, 1933 UNITED STATES PATENT` OFFICE ALFRED ALSAKER, WELDON O. HAMPTON, ANI) CHARLES A. KOERNEB, OF CHICAGO, ILLINOIS, ASSIGNORS TO THE DELTA-STAR ELECTRIC COMPANY, OF CHICAGO,

ILLINOIS, A CORPORATION OF ILLINOIS HORIZONTAL BREAK DISCONNECTING SWITCH i Application` led April 80, 1930. Serial No. 448,510.

This invention relates 'to disconnect switches, and more particularly to such switches as are adapted for outdoor use, and preferably gang operation.

Switches of the kind here contemplated generally comprise a supporting base which is preferably grounded and upon which is mounted a contact supporting insulator and one or more. switch-blade-supporting or actuating insulators. In some types of switches the contact supporting insulator is rotatable while in other types it is stationary. With increasing voltages the required spacing ofthe contact and the blade from one another and the spacing of both from the supporting base becomes very great.` The insulators may be more than eight feet long and the bladevmay be more than twelve feet long. The insulator stacks are generally made of porcelain or other frangible material and therefore are not able to withstand high stresses, especially in bending' Disconnect switches are infrequently operated, being required to stand perhaps for years in a given position, during which time they are exposed to all sorts of adverse weather. While the switch is closed, the

' lcontact and the end of the switch blade in cracking of the insulator. s In the prior art Ywith which we are familiar this has been done by exerting either a longitudinal or a twisting motion to the blade prior to the swinging thereof away from the contact. This is not quite satisfactory in that it induces certain cantilever or bending stresses in the blade actuating insulator. In addition, if the bind between the blade and the contact is strong the contact may be drawn with the blade in its longitudinal movement thus causing bending and possible cracking of the contact supporting insulator. Other forms'of ice breaking movements have beenv p -developed wherein-.the contact as well .as

the blade are actuated to break the bind between them. These` constructions of the past L vention to provide a high voltage disconnect e switch having a powerful ice breaking movement and wherein the bending stresses in the insulators are reduced to a minimum or entirely eliminated. This is accomplished in the embodiments of our invention herein il'- lustrated by making the contact supporting insulator rotatable and providing engagement between the contact and the blade on the opposite sides of the axis of rotation of the contact. To open the switch the contact is first turned so as to twist the same free of any bind between it and the blade, and then the blade is swung to the open position. Due to the fact that the contact is engaged by the blade on the opposite sides of its axis of rotation and preferably at equal distances from its axis of rotation the bending stress in the contact supporting insulator is eliminated. During this ice breaking movement the switch blade may be maintained stationary 'or it may be given a slight reciprocating or oscillating movement to assist in breaking the bind between it and the contact.

The contacts are preferably of the pressure area type. The design is such as to obtain as much contact area as possible. When this is done the pressure need not be tremendously high in order to carry say 600 amperes continuously. The contacting ends of the blade and Contact are so constructed as to relieve the pressure between them when the contact is rotated to open the switch, thereby relieving the switch blade and its supporting insulator of the stress otherwise incident to the overcoming of this pressure when the switch is to be opened. The contact design is such that the full contact area and pressure will be obtained even though lost motion should develop in the operating mechanism. This is accomplished, in the embodiment herein illustrated, by making one of the contact engaging portions U-shaped and moving it to embrace the other contact, after which one of the contacts is twisted or turned into firm engagement with the other. As shown the U-shaped contact is mounted at the end of the switch blade and is adapt,

of its actuating insulator'andl also at rightangles to the axis of rotation of the contact which is engaged by the blade. The present invention is more particularly concerned with a horizontal break switch, that is, one wherein the switch blade moves in a substantially horizontal plane. the blade is at right angles to the axes of rotation of the respective rotatable insulators rather than coincident with these `axes as in the case of the vertical break switch. This introduces a special problem in the design of the contacts so that the engagement between the end of the switchblade and the contact may take place upon the opposite sides of the axis of rotation ofA the rotary contact. We overcome this diiiculty in the embodiment of the invention herein illustrated, by making the contacting end of the blade in the form of a fork or prong the tines of which extend horizontally and at right angles to the blade. The cooperating contact comprises a substantially rectangular vertically extending bar. This arrangement may be reversed if desired. IVhen the switch is closed the rectangular contact is disposed between the tines of the prong and with its larger side reaching between the tines.l To open the switch the blade is maintained stationary while the contact is rotated through an angle to bring the larger side of the rectangular contact into a position at right angles to the tines of the prong. The axis of rotation ofthe contact (or of the prong if Athe construction is such that the rectangular contact is mounted on the switch blade) is coincident with the axis of rotation of its actuating insulator which axis extends midway between the contacting edges, hence there is no tendency to produce bending stresses in the actuating The plane of motion of insulator. By this arrangement even if the contact and the blade are frozen fast there will be no tendency to pull orthrust the switch blade supporting insulator.

As previously stated, the blade supporting insulator and the contact supporting insulator are both rotatable. We prefer to use a common actuating means for rotating both of .the insulators. The driving means is preferably connected tothe blade suporting insulator and a driving connection is` established between this insulator and the blade may be mounted upon its supporting insulator without any lost motion, and lost motion may be introduced between the insulator and the means for actuating the same.

The attainment of the above and further objects of the present invention will be apparent from the following specification taken in conjunction with the accompanying drawings illustrating a few preferred embodim nts of our invention.

In t e drawings:

Figure 1 is a side view of a switch constructed in accordance with our invention;

Figure 2 is a plan view thereof;

Figure 3 is a fragmentary sectional view showing the manner of supporting the switch blade upon the rotary insulator;

Figure 4 is a fragmentary sectional view taken along the line 4-4 of Figure 3;

Figure 5 is a diagrammatic view showing the manner of operation of the switch op-l erating cranks;

Figure 6 is a similar diagrammatic view showing the corresponding operation of the switch contact and Aof the switch blade; and

Figure 7 is a side view of a modified form of switch constructed in accordance with our invention.

Reference may now be had more particularly to Figures 1 and 2. The switch'shown in these figures comprises a grounded supporting base 1 which may be of any standard construction. As shown, this base comprises an inverted channel member. A central insulator stack 2 is rotatably mounted upon the base by` means of a suitable bearing 3 which ispreferably of a construction such as shown 1n the pending application of Alfred Alsaker, Serial No. 137 ,926, =filed September 27, 1926, although it is to be understood that any other preferred form of bearing may be used if desired. The insulator stack 2 comprises a number of petticoat insulators 4 of a construction well known in the art and secured together in the usual manner. Each insulator is shown as including an insulator pin 5 for mounting the insulator and an insulator cap 6 secured to the top of the insulator for facilitating the mounting of something upon the insulator. The insulator pin of the bottom insulator of the stack 2 is secured to the rotatable element of the bearing 3 in a manner such as is shown in the above referred to application of Alfred Alsaker, and the bearing itself is secured to the channel base 1 in any approved manner, such for instance as shown in that application. A switch blade 10 is mounted upon the top of insulator section 4 of the insulator stack 2 in a manner such as is shown more particularly in Figures 3 and 4 to which reference will be made as the description proceeds. It may be suilicient to state for the present that this switch blade is not ri 'd with respect to 'the insulator stack but t at the insulator stack is permitted a limited degree of motion without aifecting the blade 10, but that further rotation of the insulator stack 2 will bring about a rotation of the blade 10.

A pair of insulator stacks 15 and 16 are rotatably mounted upon the channel base 1 by means of bearings 17 and 18, respectively, which bearings may be of a construction such as the bearing 3. The insulator stacks 15 and 16 may be of any approved construction and have been illustrated as of the same type as the insulator stack 2. The -lower section of the insulator 15 is provided with an insulator pin 2O for mounting the same, and the upper portion of the insulator stack 15 is provided with an insulator cap 21 for providing a support for a contact and a line terminal. Likewise the insulator stack 16 is providedilwith an insulator pin 24 and an insulator cap 25 for a like purpose. A spindle 30 is suitably bolted to the insulator cap 25 and passes through a cylindrical shell 31 supported thereby. The shell 31 is rotatively mounted upon the member30 so that upon rotation of the member 30 the shell 31 need not rotate. The shell 31 provides a support for a line terminal 32 which is secured thereto and which is adapted to receive a line wire. The spindle 30 extends through the shell 31 and has a contact 35 secured thereto or formed integrally therewith. Thus the contact 35 rotates with the insulator stack 16. A flexible conductor 37 connects the terminal 32 with the contact 35.

The contact 35 is adapted to cooperate with a contact 40 carried by the end of the blade l0. The contact 40 is U-shaped, and

is adapted to receive the contact 35 between the arms thereof. The Contact 35 is rovlded with two contacting faces 41 and) 42 for engaging the arms of Athe contact 40. y

The contact 35 is mounted centrally of the insulator stack 16 so that the axis of rotation of the insulator stack, which is necessarilyalso the axis of rotation of the contact35, passes through the center of the contact thereby placing the contacting -faces 41 and 42 on the opposite sides ofthe axisof rotation of the contact 35'and at equal distances from the axis of rotation. As lavresult when the contact 35 is rotated `withy respect to the contact 40'to break anyibondthat may have formed between the two this contact 35 does not tend to .swing the blade 1() in either direction. Thisv isa distinctV improvement over switches of the .pastv with which we are familiar and wherein the contact as well as the blade is' rotated in'that in the prior switches the rotation -of` vthe contact corresponding to the'. contact 35 tends to draw the switch blade with it. Hence, in such construction, ifv there isa strong bond between the contact and the switch blade, as may result from corrosion The insulator stack 15 is provided with acontact identical to the contact 35 and with a line terminal identical to the terminal 32. At the end of the switch blade adjacent the insulator stack 15 there is provided a. contact 40 identical with the contact 40 at the opposite end of the switch blade. The contacts 40 and 40 face in opposite directions as may be clearly seen from Figure 2.

To open the switch the three insulator stacks 2,15 and 16 are simultaneously rotated in a manner to be more fully set forth as the description proceeds. As previously stated, a lost motion is introduced between the insulator stack 2 and the blade 10 so that upon the initial rotation of this insulator stack the blade may remain stationary while the contacts are rotating. The manner of mounting' the switch blade upon its supporting insulator whereby this lost motlon is obtained is shown in Figures 3 and 4 to which reference may now be had. A spindle 50 having a base 51 is secured to the insulator cap 6 of the top insulator section spindle between the blade holder 53 and the base of the spindle. One end of the spring 55 bears against a pin 56 which is secured to the base of the spindle whereas the other end of the spring bears against a pin 57 which is secured to the blade holder 53. Except for the spring the blade holder 53 is free to remain stationary during the rotation of the spindle. If desired this amount of rotation may be limited to about fifteen or twenty degrees by the location of a suitable stop upon the spindle 50 which stop engages a cooperating stop upon the blade holder 53 after a relative rotation bet tween. the twol of about fteen degrees.

. Such. abutment means may take the form of a pin 58 driven into the spindle 5() above the spring 55 and abutting against the pin 57 after a predetermined rotation of the spindle 50 inthe switch opening direction in the event that 'the blade is not released prior to the abutment of the pin 58 against the pin 57. This abutment means may of course be omitted if desired. 4

The central insulator stack 2 is rotated by means of a crank 60 which is secured to the rotatable member of the bearing 3. While this crank may be of any approved construc-V 7 clamped. The crank may be secured to the bearing in any adjusted position thereof. The crank 60 is rotated Aby the usual switch operating mechanism in a manner well known in the art and forming no part of the present invention. A pair of cranks 61 and 62 are secured to the rotatable member of the bearing so as to be rotated therewith. The crank 61 is connected to the rotatable member of the bearing 17 by means of a connecting rod 63 and a crank 64. In a like manner the crank 62 is connected to the rotatable member of the bearing 18 by means of a connecting rod and a crank 66. The cranks 64 and 66 may each be of a construction such as is shown in the pending application of Alfred Alsaker and Elias S. Corneliussen above referred to, although any other preferred form of crank may be used if desired.'Y It may thus be seen that upon actuation of the crank 60 to rotate the center insulator stack 2 a turning moment is ap' and 6 which show the position of the various operating parts when the switch is closed. These figures show only the right lhand half of the switch of Figure 1 it being understood that the left hand half vof th1s switch. 70

rection as seen. in Figure 2, hence the crank p 62 of Figure 5 lis rotated in a clockwise direction. Assume a uniform rotation of the crank 62. The free or driving end of the crank 62 moves from its closed position at a to its open position at e assing through the intermediate positions c, and Z. As the crank 62 moves from the position a to the position; d the crank 66 is rotated in alcounter clockwise direction from the position a to the position (Z. At thef` position d the crank 62 and the connection rod 65 are in alignment; hence the position d is the extreme position for the crank 66. Further rotation of the crank 62 from the position d to the position e results in a reversal of the direction of rotation of the crank 66 which now is turned in a clockwise direction to the position indicated at e for the crank 66. As previous'- ly stated the crank 66 is locked to the rotatable element of the bearing 18 to-which the insulator stack 16 is bolted, hence the insulator stack 16 and with it the contact 35 have an angular motion identical with the motion of the crank 66.' The contact 35 is thus rotated from the position shown in full lines on Figure 6 in a counter-clockwise direction through the positions b and c to the position indicated at d and thereafter it is rotated in the opposite direction to the position indicated at e.

During this interval the central rotary insulator stack rotates with a uniform angular motion identical with the motion of the crank 62. The pin 56 which moves integrally with the insulator 2 therefore assumes the successive positions b, 0', d and e as indicated in Figure 6.l During the interval of motion of the crank 62 from the position' a to the position fb the switch blade may remain stationary 1f there is even a slight force tending to hold the free end of the blade in engagement with its contact. Rotation of the insulator stack 2 merely stores energy in the spring 55. When the crank 62 reaches the position b the contact 35 is out of engagement with the contact 40 as may be seen from Figure 6; hence there is no further tendency for the contact 35 to resist turning of the switch the switch blade 10 from the position shown in full lines, which is the closed position and also the position b, through the successive positions c, d, and e, the posi# tion e being the full switch open position of the blade. A similar action takes place between the contact 40 (Figure 2) at the opposite end of the switch blade 10 and the corresponding contact mounted upon the insulator stack 15.

To close the switch the crank 60 (Figure l) is rotated in the opposite direction thus rotating the crank 62 in a counter-clockwise direction. The switch'blade is moved to the full closed position and thereafter they contact 35 is further rotated into firm electrical contact with the arms of the contact y cause of its hardness and resistance to wear,

i *.contact, the other arm being free to also because of its springy quality and resistance to corrosion. Because of this springy quality it is preferable to make thel U-shaped contact 40 of aluminum bronze since the arms of this contact have a certain amount of resiliency in order that they may be spread apart by the contact 35 to establish rm electrical engagement with that contact. When the contact 35 is out of engagement with the contact 40 the arms of this last mentioned contact are closer together than the distance between the opposite faces 41'-42 of the contact 35. As a result of this arrangement the springy quality of the contact 40 maintains a firm' electrical engagement of this contact with the contact 35. The amount of -springiness in the contact 40 is .appreciable due to the fact that this contact 1s secured to the end of the switch blade 10 at one of the arms of the Per' mit an appreciable` spreading. If both the lfork and the contact were made of copper the friction between them would be considerable, not only due to the increased coeliicients of friction but mainly because of the 'binding action of the two films of copper oxide that would form thereat. While the zuse of aluminum bronze contacts is preferred we do not wish to be limited to its use as copper or other metal may also be used.

'This switch includes an insulator stack 2 and anlinsulator stack 15 both of construc- .tions similar to the corresponding stacks of Figure 1. These insulators are mounted in the same manner as has been previously described in connection with the switch shown in Figure 1 and the rotary insulator 2 is rotated by means of a crank such as 60 in a manner as previously described. The rotary insulator 15 is rotated from the insulator 2 in the same manner as is the corresponding insulator of Figure 1. This switch is in all particulars analogous to the left hand half of the switch of Figure 1 differing therefrom in that we have provided a terminaly upon the insulator stack 2 for receivin a supported by the insulator 2 in a manner aline conductor, said terminal correspondingI function to the terminal 32 of Figu -In this construction the switch blade 10 `is mounted upon a blade holder 53 which is sol analogous to that shown in Figures 3 and 4. The spindle member which is mounted on top of the upper insulator cap 6 of the Iinsulator stack 2 Aextends beyond the switch blade andhas a cylindrical member 31 corresponding to the cylindrical member 31 of Figure 1 mounted thereon. This cylindrical member is supported by the spindle but is freely rotatable with respect thereto. Hence when the insulator stack 2 and with it the supporting spindle is rotated the cylindrical member may remain stationary. Suitable anti-friction bearing members are provided between the cylindrical member 31 and' the spindle as is also the case with reference to the cylindrical member 31 of Figure 1. The member 31 is provided with a. line terminal 70 for receiving a line conductor,

and a iexible lead 72 is provided for extending the circuit from the terminal 70 to the switch blade 10.

In compliance with the requirements of los the patent statutesf we have herein shown and described a preferred form of our lintacting portions on the opposite sides of the axis of rotation of theinsulator, a cooperating switch blade pivotally mounted on the other insulator about a pivot coincident with the axis of rotation of said other insulator, and having a limited amount of motion with reference thereto, and means on the blade for establishing engagement with the portions of the contact on the opposite sides of the aXis of rotation of the contact.

2. An electric switch including a pair of y rotary insulators, a contact member mounted on one of the insulators and'includin contacting portionson the opposite si es of the axis of rotation of the insulatorfa.switch blade mounted on the other insulator and movable in a plane at a substantial angle toy the axis of rotation of the contact, means on the blade for establishing engagement with the portions of the contact on the opposite sides of the axis of rotation of the contact, and means for openin the switch, said means including means or actuating first the contact and including a lost motion connection for then actuatin the blade.

3. An electric switch inclu ing a rotatable contact having` contacting portionson opposite sides of the axis of rotation thereof, aV switch blade movable at a substantial angle to the axis of rotation of' the contact into simultaneous engagement with both contacting portions, and means for opening said switch, said means including means for actuating first the contact and then the blade,

4. An electric switch including a pair of cooperating contacts movable in the same plane, and an operating mechanism ei'ective by a continuous motion to successively actuate both contacts.

5. An electric switch including a pair of cooperating contacts movable in the same plane, and an operating mechanism effective by a continuous motion to actuate first one contact then the other contact, there being a lost motion between the operating mechanism and at least one of the contacts.

6. An electric switchhaving a relatively short switch contact and a relatively long switch blade, and means for rotating the blade and the contact about parallel axes, said contact and said blade engaging one another at two points on opposlte sides of the axis of rotation .of the contact.

7. 'An electric switch including a supporting base, a rotatable bearing mounted thereon, an insulator mounted on the rotatable portion of the bearing, a switch blade mounted on the insulator and rotated thereby, a pair of spaced bearings mounted on the base on opposite sides of the first mentioned bearing, insulators mounted on each -of the rotatable elements of the last mentioned bearings, and contacts mounted on the last mentioned insulators and adapted to be engaged by the blade, each of the contacts including contacting portions on the opposite sides of the axis of rotation thereof,

and said blade including contacting members of each of the contacts.

-work extending from therotating mechanism for rotating each of' the other two insulators, said linkwork including a crank ad- Y jacent each ofthe two last mentioned insulators and links for rotating the cranks, said links making an angle substantially greater than 90 with their respective cranks when the switch is in the closed position.

9. An electric switch including a supporting base, a rotatable bearing mounted thereon, an insulator mounted on the rotatable portion of the bearing, a switch blade mounted on the insulator and rotated thereby, a pair of spaced bearings mounted on #the base on 'opposite sides of the first mentioned bearing, insulators mounted on each of the rotatable elements of the last mentioned bearings, contacts mounted on the last mentioned insulators `and adapted to be engaged by the blade, each of the contacts including contacting portions on the opposite sides of the axis of rotation thereof, and said blade including contacting members for engaging both of the contacting portions of each of the contacts, means for rotating the first mentioned insulator, and a linkwork extending from the rotating mechanism for rotating each of the other two insulators, said linkwork including a crank adjacent each of the two last men-y tioned insulators and links for rotating the cranks, said links making an angle substantially greater than 90 with their respective cranks when the switch is in the closed position. y

, 10. An electric switch including a supporting base, `a rotatable bearing mounted thereon, an insulator mounted on the rotatable portion of the bearing, a switch blade mounted on the insulator and rotated thereby, a pair of spaced bearings mounted on the base on oppositeisides of the first mentioned bearing, insulators mounted on each of the rotatable elements of the last mentioned bearings, contacts mounted on the last mentioned insulators and adapted to be engaged by the blade, and means for successively rotating the contacts and the blade to open the switch.

11. An electric switch includinga supporting base, a rotatable bearing mounted thereon, an insulator mounted on the rotatable portion of the bearing, a switch blade mounted on. the insulator and rotated thereby, a pair of spaced bearings mounted on the base on opposite sides of the first mentioned bearing, insulators mounteflon each of the rotatable elements of the last mentioned bearings, contacts mounted on the last mentioned insulators and adapted to be engaged by the blade, and means for rotating the contacts and the blade to open the switch, said means including a lost motion connection for permitting the blade toremain stationary during a predetermined substantial portion of the switch opening movement of the contacts.

12. An electric switch including a supporting base, a rotatable bearing mounted thereon, an insulator mounted on the rotatable portion of the bearing, a switch blade mounted on the insulator andV rotated opposite sides of the axis of rotation thereof,

:and said blade including contacting ymembers for engaging both lof .the contacting portions of each of the contacts, and means for successively rotating the contacts and the blade to open the switch.

13. An electric switch including a supporting base, a rotatable bearing mounted thereon, an insulator mounted on the rotatable portion of the bearing, a switch blade mounted on the insulator and rotated thereby, a pair of spaced bearings' mounted on the base on opposite sides of the first mentioned bearing, insulators mounted on each of the rotatable elements of the last mentionedI bearings, contacts mounted o n the last. mentioned insulators and adapted to be engaged by the blade, each of the contacts including contacting portions on the opposite sides of the axis of rotation thereof, and said blade including contacting members for engaging both of the contacting ortions of each of thel contacts, and means or rotating the contacts and the blade vto open the switch, said means including a lost motion connection for permittingY the blade to remain Astationary during a predetermined substantial portion of the switch opening movement of the contacts'.

14. An electric switch including a rotatable insulator, a switch blade pivotally mounted on the insulator atthe axis of rotation thereof whereby upon the initial rotation of the insulator the blade remains stationary, spring means for urging the blade to move as a unit with the insulator, a second rotary insulator, and a. contact mounted thereon and adapted to be engaged tation of the insulator the bladel remains` stationary, spri'ng means for urging the blade to move as a unit with the insulator, a second rotary insulator, a contact mounted thereon and adapted to be engaged by the blade, and a mechanical connection between the two insulators whereby upon rotation of p one insulator the other is rotated therewith. 16. An electric` switch including a rotatable actuating insulator, a switch vblade pivotally mounted thereon and actuated thereby, the pivot of the switch blade being coincident with the axis of rotation of the insulator, whereby upon the initial rotation of the insulator the blade may remain stationary, and spring means between the blade and the insulator tending to maintain them in a predetermined angular position with res ect to one another. v

1 An electricv switch including a blade,

a contact adapted to be engaged thereby, and means for successively rotating the two about parallel axes.

18. An electric switch including a blade,-

a contact adapted to be .engaged thereby, and means for sucessively rotating irst the contact and then the blade, the blade and the contact being ,rotated about parallel axes.

19. An electric switchl including a support, a rotatable bearing mounted thereon, an insulator mounted on the rotatable' portion of the bearing, a switch blade mounted on the insulator and'rotated thereby, a bearing mounted on the support and spaced" from the iirst mentioned bearing, an insulator mounted onthe rotatable. element of the last mentioned bearing, a contact mounted on `the last mentioned insulator and adapted to be engaged by the blade, and means for successively rotating the contact and the blade to open the switch. y

20. An electric switch including a. pair of spaced rotatable insulators, a Contact mounted on one of the insulators, a cooperating blade pivotally mounted' on the other insulator about an axis coincident with the axis of rotation of, said other insulator whereby vthe blade may remain stationary during rotation of its supporting insulator, and means for opening the switch, said means comprising means yfor simultaneously rotating both insulators whereby the blade initially remains stationary while the contact is rotated, and stop ymeans eii'ective after a redetermined rotation of the blade supportlng insulator for thereafter rotating the blade with its insulator. y

21. A switch including a pivotally mounted contact, a blade movable into and out of engagement with the contact, means including a rotatable member for supporting and actuating the blade, said blade being pivotally supported on said member about a pivot coincident with the axis of rotation of said member, means for rotating the contact and the blade supporting member, and means effective after al predetermined rotation ofthe blade su porting member for forcing the blade to t ereafter move with said member.

In witness whereof, rWe hereunto subscribe our names this 22nd day of April, 1930.

ALFRED ALSAKER. VVELDON O. HAMPTON CHARLES A. KOERNER. 

